Shot blasting is a cleaning process that removes sand, scale and other debris from workpieces, such as engine components or other articles, by impelling abrasive particles towards the workpieces. Although shot blasting has been used for many years, certain limitations and disadvantages of the shot blast machines of the conventional techniques in the art have not, until this time, been overcome. These limitations and disadvantages include the less-than-optimal efficiency of the cleaning process.
Less-than-optimal efficiency of the cleaning process typically occurs during the shot blasting of workpieces with uneven surfaces. In these situations, the workpieces must be tumbled in nearly dozens of different angles towards the path of abrasive particles. To assure proper cleaning of the workpieces, the shot blast machines of the conventional techniques in the art tumble the workpieces for an extended time, in hope that the workpieces are tumbled in the right direction. The extension of the cleaning cycle results in less-than-optimal efficiency of the cleaning process, however, and a better method for insuring the proper tumbling action is desired.
Less-than-optimal efficiency of the cleaning process also occurs because of the ineffective control over the production rate of the shot blast machine. The shot blast machines of the conventional techniques in the art include a belt configuration on a chain and slat system which are inclined or are equipped with pusher ridges to forward workpieces in a spiral motion. Also in use are systems that use a barrel for supporting and tumbling workpieces under the path of abrasive particles. These barrels are typically tilted relative to the horizontal, which allows the workpieces to tumble in a helical or spiral pattern from an ingress of the barrel to an egress. The duration of a cleaning cycle is hence defined as the time necessary for the workpieces to travel from ingress to egress. On most shot blast machines of the conventional techniques in the art, the duration of the cleaning process is difficult, if not impossible, to adjust. Since different workpieces may require a different duration, a better method of insuring the effective control over the duration is desired for an effective and efficient cleaning process.